Academic literature on the topic 'Hyaluronan brush'

Although up to several microns thick, the pericellular matrix is an elusive structure due to its invisibility with phase contrast or DIC microscopy. This matrix, which is readily visualized by the exclusion of large particles such as fixed red blood cells is important in embryonic development and in maintenance of cartilage. While it is known that the pericellular matrix which surrounds chondrocytes and a variety of other cells consists primarily of proteoglycans and hyaluronan with the latter binding to cell surface receptors, the macromolecular organization is still speculative. The macromolecular organization previously could not be determined because of the collapse of the cell coat with conventional fixation and dehydration techniques. Until now, there has been no way to study the dynamic arrangement of hyaluronan with its aggregated proteoglycans on living cells. In this study, the arrangement and mobility of hyaluronan-aggrecan complexes were directly observed in the pericellular matrix of living cells isolated from bovine articular cartilage. The complexes were labeled with 30- to 40-nm colloidal gold conjugated to 5-D-4, an antibody to keratan sulfate, and visualized with video-enhanced light microscopy. From our observations of the motion of pericellular matrix macromolecules, we report that the chondrocyte pericellular matrix is a dynamic structure consisting of individual tethered molecular complexes which project outward from the cell surface. These complexes undergo restricted rotation or wobbling. When the cells were cultured with ascorbic acid, which promotes production of matrix components, the size of the cell coat and the position of the gold probes relative to the plasma membrane were not changed. However, the rapidity and extent of the tethered motion were reduced. Treatment with Streptomyces hyaluronidase removed the molecules that displayed the tethered motion. Addition of hyaluronan and aggrecan to hyaluronidase-treated cells yielded the same labeling pattern and tethered motion observed with native cell coats. To determine if aggrecan was responsible for the extended configuration of the complexes, only hyaluronan was added to the hyaluronidase-treated cells. The position and mobility of the hyaluronan was detected using biotinylated hyaluronan binding region (b-HABR) and gold streptavidin. The gold-labeled b-HABR was found only near the cell surface. Based on these observations, the hyaluronan-aggrecan complexes composing the cell coat are proposed to be extended in a brush-like configuration in an analogous manner to that previously described for high density, grafted polymers in good solvents.

Hyaluronan (HA) is a linear, regular polysaccharide that plays as a chief structural and functional component in peri- and extracellular matrices, thus contributing significantly to many basic cellular processes. To understand more comprehensively the response of the supramolecular organization of HA polymers to changes in their aqueous environment, we study the effects of Ca 2+ concentration and pH on the morphology and rigidity of films of end-grafted HA polymers on planar supports (HA brushes), as a well-defined in vitro model system of HA-rich matrices, by reflection interference contrast microscopy and quartz crystal microbalance. The thickness and softness of HA brushes decrease significantly with Ca 2+ concentration but do not change with pH, within the physiological ranges of these parameters. The effect of Ca 2+ on HA brush thickness is virtually identical to the effect of Na + at 10-fold higher concentrations. Moreover, the thickness and softness of HA brushes decrease appreciably upon HA protonation at pH less than 6. Effects of pH and calcium ions are fully reversible over large parameter ranges. These findings are relevant for understanding the supramolecular organization and dynamics of HA-rich matrices in biological systems and will also benefit the rational design of synthetic HA-rich materials with tailored properties.

Electron microscopy after rotary shadowing and negative staining of the large chondroitin sulphate proteoglycan from rat chondrosarcoma, bovine nasal cartilage and pig laryngeal cartilage demonstrated a unique multidomain structure for the protein core. A main characteristic is a pair of globular domains (diameter 6-8 nm), one of which forms the N-terminal hyaluronate-binding region. They are connected by a 25 nm-long rod-like domain of limited flexibility. This segment is continued by a 280 nm-long polypeptide strand containing most chondroitin sulphate chains (average length 40 nm) in a brush-like array and is terminated by a small C-terminal globular domain. The core protein showed a variable extent of degradation, including the loss of the C-terminal globular domain and sections of variable length of the chondroitin sulphate-bearing strand. The high abundance (30-50%) of the C-terminal domain in some extracted proteoglycan preparations indicated that this structure is present in the cartilage matrix rather than being a precursor-specific segment. It may contain the hepatolectin-like segment deduced from cDNA sequences corresponding to the 3′-end of protein core mRNA [Doege, Fernandez, Hassell, Sasaki & Yamada (1986) J. Biol. Chem. 261, 8108-8111; Sai, Tanaka, Kosher & Tanzer (1986) Proc. Natl. Acad. Sci. 83, 5081-5085; Oldberg, Antonsson & Heinegård (1987) Biochem. J. 243, 255-259].

As a Food and Drug Administration (FDA)-approved molecular-targeted chemotherapeutic drug, sorafenib (SF) can inhibit angiogenesis and tumor cell proliferation, leading to improved patient overall survival of hepatocellular carcinoma (HCC). In addition, SF is an oral multikinase inhibitor as a single-agent therapy in renal cell carcinoma. However, the poor aqueous solubility, low bioavailability, unfavorable pharmacokinetic properties and undesirable side effects (anorexia, gastrointestinal bleeding, and severe skin toxicity, etc.) seriously limit its clinical application. To overcome these drawbacks, the entrapment of SF into nanocarriers by nanoformulations is an effective strategy, which delivers SF in a target tumor with decreased adverse effects and improved treatment efficacy. In this review, significant advances and design strategies of SF nanodelivery systems from 2012 to 2023 are summarized. The review is organized by type of carriers including natural biomacromolecule (lipid, chitosan, cyclodextrin, etc.); synthetic polymer (poly(lactic-co-glycolic acid), polyethyleneimine, brush copolymer, etc.); mesoporous silica; gold nanoparticles; and others. Co-delivery of SF and other active agents (glypican-3, hyaluronic acid, apolipoprotein peptide, folate, and superparamagnetic iron oxide nanoparticles) for targeted SF nanosystems and synergistic drug combinations are also highlighted. All these studies showed promising results for targeted treatment of HCC and other cancers by SF-based nanomedicines. The outlook, challenges and future opportunities for the development of SF-based drug delivery are presented.

AbstractTailoring interfaces with polymer brushes is a commonly used strategy to create functional materials for numerous applications. Existing methods are limited in brush thickness, the ability to generate high-density brushes of biopolymers, and the potential for regeneration. Here we introduce a scheme to synthesize ultra-thick regenerating hyaluronan polymer brushes using hyaluronan synthase. The platform provides a dynamic interface with tunable brush heights that extend up to 20 microns – two orders of magnitude thicker than standard brushes. The brushes are easily sculpted into micropatterned landscapes by photo-deactivation of the enzyme. Further, they provide a continuous source of megadalton hyaluronan or they can be covalently-stabilized to the surface. Stabilized brushes exhibit superb resistance to biofilms, yet are locally digested by fibroblasts. This brush technology provides opportunities in a range of arenas including regenerating tailorable biointerfaces for implants, wound healing or lubrication as well as fundamental studies of the glycocalyx and polymer physics.

L'adhésion des cellules à la paroi des vaisseaux sanguins est un processus complexe. Les globules rouges doivent s'éloigner de la paroi du vaisseau pour éviter la formation de caillots, tandis que les cellules immunitaires peuvent migrer dans les tissus. Ce processus repose sur le glycocalyx, une couche de macromolécules couvrant la paroi des vaisseaux. Cependant, nous ne comprenons pas complètement comment les propriétés du glycocalyx (souplesse, épaisseur, composition des récepteurs) affectent cette régulation. Notre hypothèse est que l'adhésion sélective des cellules fait intervenir des facteurs mécaniques et biochimiques. Il est difficile d'étudier ce phénomène dans de vrais vaisseaux sanguins, c'est pourquoi mon étude s'est concentrée sur le développement d'une plateforme in vitro. Cette plateforme combine un modèle de glycocalyx avec des modèles synthétiques de globules blancs sous flux, permettant un contrôle précis des paramètres physiques et biochimiques du modèle de glycocalyx et des modèles de cellules.Le modèle de glycocalyx nouvellement développé comprend plusieurs ingrédients clés dont les propriétés sont étroitement contrôlées : une brosse d’acide hyaluronique (HA, un composant essentiel du glycocalyx endothélial) est combinée à la sélectine P (une molécule d'adhésion à la surface des cellules endothéliales qui joue un rôle essentiel dans l'orientation des leucocytes). En m'appuyant sur l'expérience précédente de mon groupe de recherche, j'ai utilisé une bicouche lipidique supportée sur une lamelle de verre (SLB) portant une monocouche de streptavidine (SAv), qui peut lier des molécules biotinylées par l'intermédiaire de liaisons biotine-SAv. Je présente ici un contrôle de la mobilité dans le plan des molécules ancrées à la bicouche lipidique fluide en utilisant le glutaraldéhyde (GTA) comme agent de réticulation pour la SAv. Des densités de greffage contrôlées de chaînes d'HA biotinylées à une extrémité et de différentes longueurs permettent de créer des brosses aux propriétés mécaniques différentes. Je présente également une nouvelle méthodologie permettant d'ajuster quantitativement la densité de greffage de molécules biotinylées plus petites, qui est utilisée ici pour contrôler la densité de greffage d'une "protéine adaptatrice" pour l'ancrage de la P-sélectine. Le nouveau modèle in vitro du glycocalyx permet ainsi de contrôler la mobilité latérale, la densité de surface et l'orientation de deux molécules fonctionnelles distinctes.Le deuxième élément clé de la nouvelle plateforme consiste en des modèles de globules blancs, développés sur la base de microbilles disponibles dans le commerce ayant la taille d'une cellule et une fonctionalisation de surface avec de la SAv. Je présente une méthodologie pour le greffage simultané de deux types de protéines à la surface des billes : CD44 biotinylé (un ligand exprimé à la surface des leucocytes, interagissant spécifiquement avec l'HA) et PSGL-1 (un ligand de la P-sélectine). En outre, je présente une méthode permettant de contrôler la densité de surface de chacune de ces protéines.J'utilise une combinaison de méthodes comme outils de quantification et de contrôle de la qualité de la formation du modèle de glycocalyx et de la fonctionnalisation des billes : microbalance à quartz avec mesure de dissipation (QCM-D) ; ellipsométrie spectroscopique (SE), microscopie à contraste interférentiel par réflexion (RICM) ; microscopie confocale avec redistribution de fluorescence après photoblanchiment (FRAP), et cytométrie en flux.Cette plateforme nouvellement établie offre des conditions contrôlées pour l'étude de l'adhésion des cellules sanguines, reliant les interactions chimiques cellule-glycocalyx et les aspects mécaniques de la migration cellulaire sous flux. Elle est facilement complexifiable ou adaptable, permettant une compréhension de plus en plus fine de l'adhésion des cellules aux vaisseaux sanguins
Cell adhesion to the blood vessel wall is a complex, highly regulated physiological process. Red blood cells must repel from the blood vessel wall to prevent blood clotting while immune cells can be recruited from the vascular system to migrate into surrounding tissues. Cell adhesion hinges on the critical role played by the glycocalyx, a soft gel-like layer coating the vascular wall. However, how glycocalyx mechanical (softness, thickness) and biochemical (the composition and the density of surface receptors) properties affect this regulation is still poorly understood. Our hypothesis is that selective cell adhesion requires an intricate interplay of mechanical and biochemical cues. Elucidating the physical and molecular mechanisms that underpin selective adhesion directly in real blood vessels is challenging owing to the complexity and lack of control in in vivo systems. In my research, I aimed to construct an in vitro molecular interaction platform to facilitate mechanistic analyses. The platform combines a molecularly-defined model of the glycocalyx with mimetics of white blood cells under flow. While developing such a platform posed challenges, it offers the advantage of precise control over the physical and biochemical parameters of both the glycocalyx mimetic and cell mimetics.The newly developed glycocalyx model includes several key ingredients with tightly controlled properties: a brush of hyaluronan (HA, an essential component of the endothelial glycocalyx) is combined with P-selectin (an adhesion molecule on the endothelial cell surface critical for the homing of leukocytes). Building on previous experience in my research group, I employed a silica-supported lipid bilayer (SLB) bearing a monolayer of streptavidin (SAv), that can bind biotinylated molecules via biotin-SAv bonds. I introduce here a control of the in-plane mobility of molecules anchored to the fluid lipid bilayer using glutaraldehyde (GTA) as a cross-linking agent for SAv. Controlled grafting densities of one-end biotinylated HA chains of various lengths then create brushes of different mechanical properties. I also present a new methodology for quantitatively tuning the grafting density of smaller biotinylated molecules, which is deployed here to control the grafting density of an ‘adapter protein’ for anchoring P-selectin. The new in vitro model of the glycocalyx thus affords control over the lateral mobility, the surface density and the orientation of two distinct functional molecules.The second key component of the newly developed platform consists of white blood cell mimetics, developed based on commercially available microbeads with the size of a cell and a SAv coating. I introduce a methodology for simultaneous grafting of two types of proteins onto the bead surface: biotinylated CD44 (a ligand expressed on leukocyte surfaces, interacting specifically with HA) and PSGL-1 (a ligand of P-selectin). Additionally, I present a method for controlling the surface density of each of these proteins.I use a combination of methods as monitoring and quality control tools of glycocalyx model formation and bead functionalization: quartz crystal microbalance with dissipation monitoring (QCM-D); spectroscopic ellipsometry (SE), reflection interference contrast microscopy (RICM); confocal microscopy with fluorescence recovery after photobleaching (FRAP) capabilities, and flow cytometry.This newly established platform provides a controlled environment for studying blood cell adhesion, effectively bridging the divide between cell-glycocalyx chemical interactions and the mechanical aspects of cell migration under flow, including attachment and repulsion from the vascular wall. This platform holds the potential for expansion to encompass other surface adhesion molecules or to integrate multiple adhesion molecules, to gradually advance from the bottom up our understanding of the mechanisms governing cell adhesion to blood vessels